The measurement of chemical composition is necessary throughout commerce, regulatory government, and
many fields of science. Chemical analysis thus takes on many specialized forms.

To measure the chemical composition, body
of procedures and techniques required to identifying and quantifying the chemical composition of a sample of a substance.
A chemist executing a qualitative analysis seeks to identify the substances in the sample. A quantitative analysis is an attempt
to determine the quantity or concentration of a specific substance in the sample. For example, determining whether a sample
of salt contains the element iodine is a qualitative analysis; measuring the percentage by weight of any iodine in the sample
is a quantitative analysis.

To separate undesired materials from
the desired constituents requires certain separation methods or techniques. The appropriate separation method depends on the
nature of the constituent sought and of the overall sample. Chromatography
is the most generally applicable of the separation methods and has many variants according to the nature of the column packing
and the sample-constituent interaction.

What is Chromatography?

Chromatography is a non-destructive process for resolving a multi-component mixture of traces,
minor or major constituents into its individual fractions. Chromatography may be applied to both quantitative and qualitatively.
It is primarily a separation tool.

Principle Underlying Chromatography

It is based on Partition Coefficient
in which a compound describes the way in which it is distributed itself between two immiscible phases.

Different types of chromatographic techniques are available to analyze the samples, but few of the
techniques are familiar, those are High performance liquid chromatography (HPLC) and Gas Chromatography (GC). All the chromatographic
techniques have their own advantages and disadvantages. Gel permeation chromatography, in which large molecules separate according
to their size; and ion exchange chromatography, in which charged, or ionic, constituents are separated. Gas chromatography
separates the volatile constituents of a sample, and liquid/liquid chromatography separates small, neutral molecules in solution.

Why HPLC and GC having high importance compared with other techniques?